CWP 502 Bad Gateway error?

If you force PHP-FPM and you deal with 502 bad gateway error try the following

1. Check whether the status of the service using the below command.

2. Try to find the User that caused the error by checking the log files.

3. If there is a user causing the problem and the service can not start then remove the user configuration file

4. Try to start the PHP-FPM service running the following command

5. If you still have problem use the following command replacing the username with your username

6. If nothing of the above gives you peace in mind then do the following. (mostly if you are using a container)
Edit the following file

"/etc/pam.d/su"

to change all "session" variables to "OPTIONAL"

so that the file looks like this:
session--optional-- system-auth
session--optional--postlogin
session--optional--pam_xauth.so